Field of the Invention
This invention relates to the field of mechanisms. More specifically, the invention comprises a mechanism for converting linear motion into a combination of linear and rotary motion, whereby an object can be moved along a desired linear path and indexed through a desired arc of rotation. 2. Description of the Related Art
Numerous prior art devices are designed to convert rotary motion into linear motion. U.S. Pat. No. 1,016,611 to Chilton (1912) discloses a bottle filling and capping machine. This machine is comprised of a rotating carousel. A mechanism (see FIG. 10) converts the rotating motion into linear motion for the bottles. Thus, as the carousel turns, the bottles are moved up and down to the appropriate positions for the capping process.
A similar approach is taken in U.S. Pat. No. 2,517,592 to Nordquist (1950). A camming surface (designated as xe2x80x9c68xe2x80x9d in FIG. 1) is used to raise and lower jars as they move on a rotating carousel. U.S. Pat. No. 2,638,259 to Garrett (1953) uses a similar camming surface (see FIG. 1).
More camming surfaces capable of converting rotary motion to linear motion are disclosed in U.S. Pat. No. 3,139,914 to Bingham (1961) and U.S. Pat. No. 3,335,767 to Manas (1967). Like the Chilton, Nordquist, and Garrett devices, the Bingham and Manas devices convert the machine""s primary rotary motion into a reciprocating linear motion. All these devices xe2x80x94Chilton, Nordquist, Garrett, Binghan, and Manasxe2x80x94convert continuous rotary motion into rotary motion with an added reciprocating linear motion. It is significant to note that the rotary motion is always present in these devices; i.e., they are incapable of producing a purely linear motion at any point.
A different approach is disclosed in U.S. Pat. No. 4,027,767 to Gluck (1977). The Gluck device uses a slotted cylinder with a following peg riding in the slot in order to produce reciprocating linear motion (See FIG. 1). The Gluck device also uses a 6 position indexing gear (element xe2x80x9c17xe2x80x9d in FIG. 3) to index a turntable (xe2x80x9c19xe2x80x9d) through several set indexing points. Thus, the device (which is actually a combination of several mechanisms) is capable of indexing a turntable to a fixed position, moving it up and down, then indexing it to another position. In other words, it can have purely linear or rotary motion at a given point. Unfortunately, the Gluck device is rather complexxe2x80x94employing several mechanisms to achieve the desired linear and rotary motion.
Some devices are, of course, capable of converting a primarily linear motion into rotary motion One such device is disclosed in U.S. Pat. No. 5,806,404 to Sher (1998). The Sher device uses a reciprocating piston as the driving mechanism (such as found in a pneumatic driving system). A pair of pegs riding in a groove convert this reciprocating linear motion to a continuous rotary motion (see FIGS. 2, 3, and 5). The actual object being moved (a cutter head) simultaneously exhibits rotary and linear motion; i.e., the device is incapable of producing purely linear or rotary motion.
Accordingly, the prior art devices are limited in that they: (1) Are incapable of producing purely linear motion; and/or (2) Require a complex combination of several mechanisms to achieve linear motion without rotary motion.
It is desirable to index a table through a fixed arc, and to then move the table up and down in a purely linear fashion. This type of motion is useful in many processes, particularly where one wishes to bring a polar array of objects into contact with another stationary object so that some operation can be performed.
The present invention seeks to create this type of motion using only the reciprocating linear motion of an air cylinder as the driving force. Referring to FIG. 1, air cylinder 12 is affixed to base 10. Air cylinder 12 has cylinder rod 14, which moves up and down as air pressure is applied to port 16 (typically by an air hosexe2x80x94not shown). Table 18 is attached to the upper end of cylinder rod 14. FIG. 1 shows table 18 in its lowered position.
Turning now to FIG. 2, air pressure has been applied to air cylinder 12, with the result that table 18 has been lifted to its upper position. This movementxe2x80x94between FIG. 1 and FIG. 2 constitutes the linear input motion which drives the device. To lower table 18, the air pressure is shut off to air cylinder 12. Gravity then pulls table 18 back down to its lowered position.
Turning to FIG. 3, the reader will observe that table 18 has several pegs 20 spaced evenly around its perimeter. Indexer 26 is positioned close by the perimeter of table 18. Indexer 26 has slot 38 cut completely through its thickness. Pegs 20 are sized to fit within slot 38. Slot 38 is designed to convert a portion of the aforementioned linear motion into an indexing rotary motionxe2x80x94as will be explained in more detail subsequently.